Aircraft cabin rate of climb control instrument



March 24, 1953 w. B. KLEMPERER 2,632,374

AIRCRAFT CABIN RATE OF CLIMB CONTROL INSTRUMENT Original Filed April 6, 1942 Z; 7% 2g 3% D Z0 Z6 o K /6 3 O f" /5 2a i 22 13/ /7 if f 55 INVENTOR.

AfroeA/Ey- Patented Mar. 24, 1953 AIRCRAFT CABIN RATE OF CLIMB CONTROL INSTRUMENT Wolfgang B. Klemperer, Los Angeles, Calif., as-

signor to Douglas Aircraft Company, Inc., Santa Monica, Calif.

Original application April 6, 1942, Serial No. 437,921. Divided and this application March 20, 1951, Serial No. 216,567

(Cl. 98+L5) 16 Claims. 1

This invention relates to pressure regulating instruments and more particularly to such an instrument for regulating the time-rate-of-pressure-change especially useful in systems for conaircraft cabins.

than ambient flight pressure.

determined schedules.

flight pressure.

vide means for cabin too great for passengercomfort.

trolling the pressure of the air of pressurizable 5 trol the rate of air discharge from the cabin; it

will, in turn, regulate or control the time-rate-oil. This application is a division of my copending pressure-change within the cabin. pplication, Serial N0. 437,921, filed April 6, 1942, The instrument furthermore provides means. now U, 6. Patent NO, 2,549,690. In the pressure for preselecting the time-rate-of-pressure-change regulating system therein shown, as in substanso that the rate can be controlled to changefrom tiallyall such systems, the absolute pressure a given or starting cabin pressure to a desired. within the cabin is varied by controllably varying cabin pressure at any predetermined desired rate. the rate of air discharge from the cabin relative The instrument of the present invention also proto the rate of air delivery to the cabin. The air vides means which will permit or induce a change delivered to the cabin is furnished by superof pressure within the cabin, whether an increase chargers of like blowers which are capable of deor a decrease, at a preselected rate and regardless livering air to the cabin at a pressure greater of the change or rate of change of ambient or In such systems flight altitude pressure. the rate of air discharge is varied by valve means, may be used to induce a preselected rate of inthe position of which is controlled by a suitable crease in cabin absolute pressure eventhough operating means regulating the flow of vitiated the aircraft is maintained in level flight. air through an opening formed in the cabin wall. feature of the instrument is highly advantageous Considerable development has been undertaken for it permits the pilot or flight engineer to induce in the past toward providing means to control the M n apparent decrease in the simulated altitude pressure in aircraft cabins along certain preof the cabin as the aircraft continues to ,flyfin Initial effort wer dilevel flight and then at some later period of time rected toward maintaining cabin absolute presrap y descends to the ai p sure constant at an intermediate altitude when- The instrument on the other hand can be used ever flight above that altitude was attempted. m rely asalimiting or vetoing instrument toover- Control of cabin pressure at the constant value ride and limit the control action of other pressure of an intermediate altitude has been found imegulating instruments of the system to thereb practical, since it is obvious that little had been lim h r of pr re change within the cabin. achieved in isolating the passengers of the cabin In ny event, the instrument of the present l from the rather rapid changes in pressure during Vent/i011 is always operative to limit 01 regulate the ascents and descents in a region where the the -D -c e Within the air is most dense and where. the pressure thereof cabin to e p te rat changes most rapidly with changes in altitude. Other features and advantages of the invention Control mean have also been previously p will be readily understood from the following deposed which controlled cabin pressure in some tailed description taken With e accompanying predetermined relation to the change in pressure w in Wh ch the single fi re s a Sectional of the flight atmosphere so that cabin absolute View Of one embodiment of t e ent of the. pressure was varied in proportion to changes in present invention showing one form of a control The o-eau d ratio control circuit with which the instrument can be used. systems, although some improvement ov th The control instrument of the present invenconstant altitude pressure systems, did not protion, referring now to the drawing, Comprises a regulating th time ra,te of case or housing H3 having dividing or transverse pressure-change Withinthe cabin during ascents wall H forming with the other wall elements of and descentsof the aircraft at rates which prothe e a p of c bers l2 and It. The duced a time-rate-of-pressure-change Within the chamber is hermetically sealed a d communicates with the chamber l3 through a capillary The control instrument of the present invention tube is which pierces the transverse wall I I. It obviates the difiiculties had withpreviously prowill thus be seen that the chamber I2 is in reposed control systems by providing for controlling strictive communication with the chamber 13 and the time-rate-of-pressureechange Within the y change of pressure of air held by chamber cabin. This is brought about by so connecting the instrument of thepresent inventionv into .the. system as to selectively operate the meanscontrolling the position of the air discharge valve. As the instrument will, therefore, conmeans.

Thus the instrument This [Swill be slowly communicated to the c am er] 2';

Suitably mounted to the one face of the transverse wall I l and disposed Within the chamber 13 is a pressure responsive capsule assembly I5, the interior of which communicates through a short conduit 16 with the interior of the chamber 12. The exterior of the capsule assembly I5 is to be subject to cabin absolute pressure for the chamber l 3 in which the capsule assembly i mounted communicates with cabin absolute pressure through the conduit l1. It should now be seen that the capsule assembly l5 will respond to chan es in the rate of absolute pressure change within the cabin for pressure changes cannot quickly equalize in the two chambers.

The capsule assembly l5 carries at its movable end a small lug l8 to which is pivotally mounted a control arm l9 intermediate the ends of the latter. The one end of the control arm [9 is .pivotally mounted to a small bracket carried on the interior of the case Ill. The opposite end of the controlarm I 9 carries a contact element 2| which, as the capsule assembly l5 expands and contracts, moves with the arm IS in opposite directions.

Slidably mounted within the case is is a support 22 which is mounted for reciprocal movement by guide elements, one of which is indicated at 23. The position of the support 22 is recipro cally adjusted by means of a shaft 24 rotatably supported by one wall of the case in and having the inner end thereof threadedly engaged in a tapped opening formed in the support 22. As the support 22 is held against rotational movement with the shaft 24, it will be seen that rotation of the latter will produce reciprocal movement of the support 22, the direction of movement of the support 22 being dependent upon the direction of rotation of the shaft 24. To facilitate rotation of the shaft 24 the outer end thereof carries a knurled operating knob 25.

The support 22 carries a pair of lugs 26 partially supporting for rotation a shaft 21 which pierces the one wall of the case Ill to terminate at its outer end in a knurled operating knob 28. The shaft 2! is formed with a pair of spaced enlarged sections, the one section being formed with screw threads 29 opposite in pitch to screw threads 3| formed on the other enlarged section of the shaft. The threaded enlarged sections of the shaft are used to mount a pair of contacts 32 and 33 held by any suitable means desired against rotation with the shaft 21. It should now be seen that rotation of the shaft 21 through manipulation of the knob 28 will result in opposite relative movement of the contacts 32 and 33. The relative distance between the contacts 32 and 33 can, therefore, be easily changed or varied merely by rotation of the shaft 21. On the other hand rotation of the shaft 24 will produce conjoint simultaneous movement of the contacts 32 and 33.

It will now be seen that as the capsule assembly l5 expands and contracts in response to changing rates of pressure increase or decrease within the cabin, the control arm I 9 will function as a switch arm to move the contact 2i into engagement with one or the other of the switch means or contacts 32 and 33, depending upon the direction of movement of the arm I9.

The instrument includes a suitable lead-in element 34 for electrically connecting conductors 35 and 36 to the contacts 32 and 33 respectively. The conductors 35 and 33 form a portion of one embodiment of a control circuit with which the instrument of the present invention can be used. This control circuit is schematically shown in the drawing and comprises a motor 37 which, through a suitable gear train, not shown, operates a valve 38 used to control the rate of air discharge from the cabin. The motor 31 is reversible and may be energized either through the field coil 39 or 4| by power from some-suitable source such as the battery 62 to drive the valve in alternate directions depending upon the direction of rotation of the motor 31.

Automatic control of the valve 38 is eiiected through a control relay 43 which, as shown for illustrative purposes, is essentially a power amplifier in which-very small currents from a battery as can be used to selectively energize the coils 45 and 43 of the relay 43 to control a flow of relatively large current in the circuits of the motor field coils 39 and 3!. Energization of relay coil 45 causes the armature 41 of the relay 43 to move to the left, as viewed in the figure, and into engagement with a contact 38 against the action of one of a pair of centering springs 49 to complete a circuit from the battery 32 through the circuit of the field coil 39. Energization of this field coil produces such directional rotation of the motor to drive the valve 38 toward an open position to increase the rate of air discharge from the cabin.

On the other hand energization of relay coil as causes the armature 41 of the relay 43, to move to the right, as viewed in the figure, to engage with contact 5i against the action of the other of the pair of centering springs 39 to complete a circuit from the battery 42 through the circuit of the field coil 4|. The completion of this circuit, as should now be understood, causes the motor 3'! to drive the valve 38 in the opposite direction, that is toward closed position, to decrease the rate of air discharge from the cabin.

Energization of the relay 43 is in part controlled by pressure responsive means schematically shown at 52. The control means schematically shown in 52 may comprise any control elements desired which will regulate cabin pressure along some preselected or desired pressure schedule as the aircraft is flown at altitudes at which pressurization is desired. This control means could comprise either the cabin altimeter is or the pressure regulator 24 of my copending application above identified. The control means 52 is electrially connected by leads 53 and 53 to the conductors 35 and 36 respectively of the control circuit previously described. A grounding conductor 55 electrically interconnects a conductor 56 leading to the control arm i9 and conductors 55 and 56 are in turn connected to a common ground conductor 51.

To prevent overloading of the contacts forming a part of the control circuits, an electronic relay schematically indicated at 58 may be used.

It will thus be seen that if the circuit, of which the conductor 54 forms a part, is energized by the control means 52, the relay coil 45 will be energized to bring about opening movement of the valve 38. If, on the other hand, the control circuit, of which the conductor 53 forms a part, is energized, the relay coil 46 will be energized to produce closing movement of the valve 38.

Regardless of the type of control instrument 52 used, whenever in its operation it so controls the motor 31 as to produce, through the resulting movement of the valve 38, a time-rate-of-pressure-change within the cabin in excess of some preselected rate, the instrument of the present invention is operative to veto the control action sought to be effected by the instrument 52. The preselected rate of pressure change is efiected through adjustment of the-shaft 24 by manipulating the control knob 25.. which, it will be remembered, slidably moves consequently the contacts thereto.

To indicate the setting to the operator, the shaft 242carries a pinion 55; which meshes with and drives a gear 6| which carries on its front face a scale, not showrnbut which can be graduated into units of increase or decrease of. altitude perunit'of time.

.32 and 33- mounted If,. forexample, the control instrument sche-- matically shown at 52 was a control instrument such as the altimeter"!!! of my copending application and the aircraft was flying at an altitude of" 9000 feet with a simulated cabin altitude of 8000 feet and the aircraft was about to descend to' an airport, the shaft could be adjustedto position contact 32 to effect the desired-descent at the preselected rate-of-pressure-change Within-the cabin. As the'aircraftdescended to an altitude'of 8600 feet, the pilot or flight operator pressure at a rate greater than the preselected rate. The pressure within the cabin and consequently chamber I3 would immediately increase over that in chamber 12' and the larger exterior pressure would tend to collapse the capsule assembly l5. As soon as the time-rate-of-pressurechange equaled the preselected rate, the pressure capsule assembly IE will move contact 21 into engagement with contact 33 to complete a circuit through the relay coil 45. If at the time relay coil 45 is energized, relay coil 46 is also energized because of the control action of the instrument 52, the centering springs 39 will move the armature l!- into the central or balanced position in which it is out of engagement with both contacts 48 and 5!. This, of course, would immediately de-energize the motor 31 to arrest movement of the valve 38 and thus hold the valve 38 in the. position at which the rate of air discharge fromthe. cabin produced the time-rate-of-pressure-change. within the cabin equalxto the. preselected rate.

Itwill thus beseen that in this operation of the control instrument of the present invention, the instrument vetoes the control action sought to be effected by the instrument 52 and limits the rate-of-pressure-change within the cabin during the descent of the aircraft to one substantially equal to the preselected rate.

To explain other operational features of the instrument .of the present invention, let us assume thatathe aircraft is to" take off from an airportat an altitude of 500 feet and the pilot wished to maintainthe cabin ata simulated altitude of 8090 feet as the aircraft ascended-to altitudes in excess of-8000 feet. In this flight schedule, the instrument 52 would be initially set so as to be inoperative to control cabin pressure as the aircraft. ascended.

If the aircraft climbed at such a rate as to pro-- duce Within the cabin a time-rate-of-pressurechange in excess of the preselected rate, the presthe: support 22. andsure capsule assembly l5. would expand and in' expanding would move contact 2| into engagement with contact 32, thus energizingrelay coil to to produce closing movement of the valve 38. Closing movement of the valve 38will obviously decrease the time-rate+of-pressure-change-within the cabin asthe aircraft continues to ascend. So long as the aircraft was operated below the 8000 foot altitude, the control insrument of the present invention will act as the primary control instrument and maintain the time-rate-of-pressure-change Within the cabin at the preselected rate. As the aircraft approached an altitude of 8000 feet the control instrument 52 would then be set to maintain a simulated altitude of 8000' feet in the cabin as the aircraft climbed toalti tudes in excess of 8000 feet.

One of the features of the instrument of the; present invention resides in the fact that the instrument can be used to induce a time-rate-ofpressure-change Within the cabin independently of the actual flight path of the aircraft. Thus,v if the aircraft was being operated in. mountainous country and the. next scheduled landing wasto be made at an airport surrounded by mountains, the pilot or flight engineer could reset thecontrol instrument 52 to the altitudeof the airport and thus bring about movement of the valve 38. as the aircraft continued to fly in level flight. This movement of the valve obviously would produce:

would thereafter 50 control operation of the motor- 3"! as to limit the time-rate-of-pressure-change: within the cabin to the preselected, rate. even though the ambient flight pressure remained substantially constant. This feature permits the pilot to slowly increase pressure within the cabin to simulate a descent even though the aircraft continues to fly sometime thereafterin level flight and then descends rapidly to the airport.

The instrument of the present invention would be used by itself to control operation of the motor 3'! and does not require a second control instru ment such as the one schematically shownat 52. The control instrument 52, whatever be itstype, is only to effect elevation of cabin pressure over ambient flight pressure so that if the aircraft was to be operated at altitudes requiring no substantial increase of cabin absolute pressure, the in-' strument of the present invention will function to limit the-time-rate-of-pressurechange within the cabin. If, for example, no control instrument, such as schematically shown at 52, Was included in the control system,'the instrument of the present invention would, as the aircraft ascended, prevent a time-rate-of-pressure-change greater than the preselected rate. This is so, for: if .the aircraft in ascending at a rate which produced a time-rate-of-pressure-change within the cabin substantiall equal to the preselected rate, the expanding capsule assembly i5 would bring about engagement of the contact 2| with the valve closing contact 32. and thus prevent a time-rateof-pressure-change greater than the preselected rate.

It can be pointed out here that as soon asthe valve Sitcomrnences to move toward closing position, the time-rate-of-pressurechange within the. cabin would obviously decrease as the. pressure increased and the increasing pressure would tend to collapse the pressure capsule assembly l5 and if,.in collapsing, contact 25 moved into, engagement with contact 33, the. valve would be moved toward open position. The contact would thus hunt between contacts 32 and 33 as the aircraft continued to ascend. The degree of hunting of the contact 2| under the urgings of the capsule assembly 15 can be reduced by operation of the shaft 21 in the direction necessary to bring the contacts 32 and 33 into a relative position in which there is little clearance between the contact 2 I in the zero position of the control arm it, and each of the contacts 32 and 33.

In principle the described instrument is a timer or time control device because the movement of the arm [9 is dependent on the time rate of flow of air through the tube M. It will be seen that the power for operating the time control device is the pressure difference internally and externally of the capsule assembly. The device generally incorporates a reservoir (chamber 12) and a passage (tube M) for restricted flow into and out of the reservoir to vary the charge in the reservoir and the time delay provided is based on the time required for the reservoir to charge or discharge through the restricted passage. The pressure differential across the restricted passage is the difference between cabin pressure and the reservoir pressure, and the capsule assembly or bellows I5 forms in effect, a movable wall sensitive to this pressure differential. The movable wall formed by the capsule assembly is operatively connected, through the arm !9 which forms an actuator means or as will be later shown, a control effecting means for, the pressure control system or pressure control servo mechanism of the aircraft. The actuator means formed by the arm I9, as it is moved through responses of the capsule assembly !5 in accordance with the changing relationship of cabin pressure and reservoir pressure, coacts with the switch means formed by the contacts to control the operation of" the valve motor as to variably position the valve to so regulate the change in cabin pressure as to prevent an excessive rate of pressure change within the cabin. This is so for the rate of flow through the tube I 4, that is, the capability of the restricted passage to equate the pressure act- 111;; on the movable wall varies the charge in the reservoir at a given maximum rate, as cabin pressure changes in excess of that rate, and in so doing bring about movement of the actuator means to limit the change in cabin pressure to a given maximum rate. In this way the instrument delays or prolongs a change in cabin pressure from a starting pressure to a desired pressure to a degree required for the comfort of the passengers.

The contacts 32 and 33 form, as should now be understood, control means for controlling operation of the discharge valve of the system which in turn controls the rate of air discharge from the cabin. The arm l9, as it effects operation of the control means formed by the contacts, thus provides in the instrument a control effecting means. It has been seen that the control means can be rendered operative independently of the capsule assembly by variably positioning the contact means relative to the control effecting means formed by the arm i9.

The instrument of the present invention, when used in a system having another control instrument, acts in opposition to the control action sought to be effected by the other instrument to limit the time-rate-of-pressure-change Within the cabin, whether that change is produced by the other instrument of the system as reflecting a change in altitude of the aircraft or conjointly with the other instrument as when the latter is reset in flight to induce a pressure change within the cabin. It is believed now that the operation of the control instrument of the present invention, whether it be used alone to control operation of a valve such as the valve 38 or used in conjunction with some other control instrument, should be perfectly clear. In the broadest aspects of the present invention the instrument is one, as should now be recognized, which will so control the position of a discharge valve as to controllably vary the rate of air discharge from the cabin, and so control the rate as to limit the timerate-of-pressure-change within the cabin to a preselected maximum rate.

Although the now preferred embodiment of the present invention has been shown and described herein, it is to be understood that the invention is not to be limited thereto, for it is susceptible to changes in form and detail within the scope of the appended claims.

I claim:

1. An instrument for use in a system for regulating pressure in an aircraft cabin which system includes means to effect and control air outflow from the cabin, comprising: a housing to be mounted within said cabin and including means for communicating the interior of said housing with said cabin; means within said housing responsive to and motivated by the rate of pressure change within the housing; control means carried by said housing and including means adapted to be operatively connected to the means of said system efiecting and controlling outflow from the cabin for controlling operation of the same; and control effecting means within said housing for producing operation of said control means; said control effecting means actuated by said pressure change responsive means to produce an operation of said control means in response to a preselected rate of pressure change within said housing.

2. An instrument for use in a system for regulating pressure in an aircraft cabin which system includes means to effect and control air outflow from the cabin, comprising: a housing to be mounted within said cabin and including means for communicating the interior of said housingwith said cabin; a device mounted in said housing and responsive to the rate of change of air pressure within said housing and including an element movable by, and in proportion to the rate of change of said pressure; and power transmission means carried by said housing and adapted to be operatively connected to the air outflow efiecting and controlling means of said system; said power transmission means being rendered operative by movement of said element to control the time-rate-of-pressure-change in said cabin.

3. An instrument for use in a system for regulating pressure in an aircraft cabin which system includes means to effect and control air outflow from the cabin, comprising: means to be mounted within said cabin for sensing the rate of pressure change within said cabin and includ ing means for transmitting energy indicative of the rate of pressure change within said cabin; and control effecting means including means adapted to be opera-tively connected to the means of the system eifecting and controlling air outflow from the cabin for controlling operation of the same, said control effecting means actuated by the energy transmitted by said rate of pressure change sensin means and adapted to produce an operation of said outflow effecting and control-means to control the time-rate-ofpressure-changewithin saidcabin.

4. An instrument foruse in a system for regulating pressure in an aircraft .cabin, whichsYstem includes meansto effect and control air outflow from the cabin for varying the rate of air outflow, comprising: control regulating means to be mounted within saidcabin, said control regulating means including. control means adapted to be operatively associated with the means of said system effecting and controlling air outflow from the cabin for controlling operation of the same, control effecting means operatively coacting'withsaid control means foractuating the latterto control operation of the air outflow con trol means of said system, and meansincluding a' time controlled device, operatively connected to said controleffectin means to selectively operatetthe latter whereby said control enecting .means. coacts with said controlmeans-to produce apreselectedoperation of said outfiow eiiecting and controlling means. to vary the rate of-air outflow from saidcabin to thereby control the time-rate-of-pressureechange within said cabin at a..presele.cted. value as-the .air pressure in said cabin is changed from a. starting pressure to a desired pressure.

. 5. An instrument forusein a system for regulating pressure inan aircraft cabin, which system includes means to efiect. and control. air outflow acts withsaidcontrol means to produce a preselected operation of said. outflow veffectinghand controllingmeans tovary the-rate of air outflow from said cabinto-thereby control. the. timer-rateof-pressure-change within. said ,cabin at a preselectedvalueas the air pressure in said cabin is changed from a starting pressure to a .desired pressure; and presettablemeans for varying the action of-said control effecting means whereby :the time-rate-ofepressureechange within said cabin may. be preselectivelyvaried.

. 6. .An instrumentiorusein a system for. regulatingpressure inan aircraft cabin, which system includes means to efiect and control. air .outflow from the cabin for. varying the rate of air outflow,

comprising: control; regulating .means .to be mounted within. said cabin, saidcontrol regulat- :ingmeans including control means adapted. tobe operatively. associated with .the .means of; said system-effecting. and controlling lairoutflowfrom the cabin for. controlling operation. of the. same,

control efiecting means operatively .coacting with said control meansforactuating. thelatter to controloperation of. theair outflow control means of said system, andmeans; including a.- time controlled device, operatively connected. to.s -aid..con-

-trol effecting meansto selectivelyoperate the latter whereby'said control eifectingmeans coacts-with said control means to produce a preselected operation of said outflow efiecting and controlling means to vary the rat of air-outflow means in response to apreselected sure changewithin said housing.

.dering. said control means, operative to produce control operation of said outflow controlling .meanscof said system to induce cabin pressure to changeat apreselected value in accordance with they settingof said presettable means.

'7. Ari-instrument for use in a system for regulatingpressureinjan aircraft cabin which system includes means to effect and control air outflow fromflthe cabin, comprising: a housing to be mounted withinsaid cabin and including means for communicatin the interior of said housing with said, cabin means within said housing sens- ..ingtnerate of p es u eLchanse wi h nsaidhous- .ing. and including means, for vtransmitting energy indicative of therate ofpressure change within saidhousing; control means carriedby said housing and including means adapted to b opera- .tively connected to the means of said system effectin and controlling air outflow from the cabin for controlling operationof th same; and

control efiectingmeans within saidhousingactuated by the energy transmitted by. said just named means and adaptedtofproduce an operation of saidcontrol-means therebyfto controllably operate said outflow. effecting. and controlling rate. of pre 8. .An instrumentfor use in a. systern f or regulating pressure in an .aircraftcabin which system includes means to, effect. and control air .outflow from the cabin, comprising: meansto bemounted .within said cabin sensing the. rate ofpressure change within saidcabin andincludingmeans for transmitting energy indicative of the rateyof pressure changewithin saidcabin; control means including .meansadapted to be operatively Iconnected. to the means of. said system effecting and controlling air; outflow from the cabin f0r controllin operation ofthe same; ,control effecting means actuated by the energy, transmitted by said sensing means to produce.,anoperation of said control means.inresponseto a preselected rate. of pressure change within said cabin and means for rendering (said .controlmeans. Opera- -tive to produce an operation'offsaid outflow, effecting and controlling ,means. independently of said sensingmeans to induce cabin absolute pres sure to change at a'preselected rate.

9. An instrument foruse in a system for con- .trollably regulating pressure. within any aircraft cabin, which system'fincludes, meansifor supplying air under pressure and. having. air'dis'charge means for varying th raite of {air discharge from said cabin, comprising: a housingit'o bemounted within said abinfwall means, forming a, sealed .reservoirwithinsaid housing; means carried by said housing formin a restricted orifice. toIplace the reservoir in. communication with the interior ofthe-cabin for airfio'winto and .out of said reservoir in accordance with variations in. cabin vabsolute pressure; control means, including mea s. to o e ativ yconne te th ai i charge ,varying means; of said system, for con- ;tro11ing..op e ration of; the; am an c n .,-e

ifecting means actuating saidv control means whenever alpreselectedrate of chflll fi Q Qabin absolute pressure produces. a change, in. the. .1?

tionship between cabin absolute pressure and reservoir pressure to control operation of said discharge means to vary the rate of air discharge from said cabin in accordance with the relationship of cabin absolute pressure and reservoir pressure to thereby vary the time rate of pressure change within said cabin.

10. An instrument for use in a system for controllably regulating pressure within an aircraft cabin, which system includes means for supplying air under pressure and having air discharge means for varying the rate of air discharge from said cabin, comprising: a housing to be mounted within said cabin, said housing having wall means forming a reservoir; means carried by said housing forming a restricted orifice to place the reservoir in communication with the cabin for airflow into and out of said reservoir at a restricted rate to vary the air pressure in the reservoir in accordance with variations in cabin absolute pressure and to cause the changes in reservoir pressure to lag behind the changes in cabin absolute pressure; a movable wall sensitive to variations in the difierence in cabin absolute pressure and reservoir pressure; and actuator means, including means adapted to be operatively connected to said movable wall for movement thereby and to said air discharge means for producing operation of said air discharge means as said movable wall responds to variations in the difierence between cabin absolute pressure and reservoir pressure.

11. An instrument for use in a system for controllably regulating pressure within an aircraft cabin, which system includes means for supplying air under pressure and having air discharge means for varying the rate of air discharge from said cabin, comprising: a housing to be mounted within said cabin, and including wall means. forming a sealed reservoir within said housing; means carried by said housing to place the reservoir in communication with the interior of the cabin for airflow into and out of said reservoir at a restricted rate to vary the air pressure in the reservoir in accordance with variations in cabin absolute pressure; means subject to, and operable in response to a change in, the pressure of the air within said reservoir; control means, including means to be operatively connected to the air discharge varying means of said system; and control effecting means for producing operation of said control means, said control effecting means actuated by said pressure change responsive means whenever the rate of change of cabin absolute pressure produces a preselected change in the pressure of the air within said reservoir and thereby producing operation of said air discharge varying means of the system.

12. An instrument for use in a system for regulating pressure in an aircraft cabin which system includes means to effect and control air outflow from the cabin, comprising: a housing to be mounted within said cabin and including means for communicating the interior of said housing with said cabin; means within said housing sensing the rate of pressure change within said cabin and including means for transmitting energy indicative of the rate of pressure change within said cabin; control means carried by said housing and including means adapted to be operatively connected to the means of the system effecting and controlling air outflow from thecabin for controlling operation of the same;

control efiecting means for producing operation of said control means; said control effecting means actuated by the energy transmitted by said first named means and adapted to produce an operation of said control means to effect operation of said outflow effecting and control means to control the time-rate-of-pressure-change within said cabin; and means for selectively adjusting the action of said control effecting means to vary the actuation thereof in response to energy transmitted by said sensing means thereby to vary the operation of said outflow effecting and controlling means and the resultant tin1e-rate-of-pressurechange within said cabin.

13. An instrument for use in a system for controllably regulating pressure within an aircraft cabin, which system includes means for supplying air under pressure and having air discharge means for varying the rate of air discharge from said cabin, comprising: a'housing to be mounted within said cabin, said housing having wall means forming a reservoir; means carried by said housing to place the reservoir in communication with the cabin for airflow into and out of said reservoir at a restricted rate to vary the air pressure in the reservoir in accordance with variations in cabin absolute pressure; control means carried by said housing and including means to be operatively connected to the air discharge means of said system and adapted to operate the same to vary the rate of air discharge from said cabin; pressure responsive means having one side subjected to the pressure within the reservoir; control effecting means mounted within said housing and actuated by, said pressure responsive means to produce operation of said control means; means, including manually operable means, for applying a control force to said control effecting means to produce a preselected operation of said control means whereby the latter is actuated to so control operation of said air discharge means as to vary the rate of air discharge from said cabin and in turn produce a preselected time-rate of-pressure-change within the cabin.

14. A pressure regulating instrument for use in a system for regulating pressure in an aircraft cabin whereinto air is supplied by an air delivery means and from which vitiated air is discharged through a valve regulated by electro-responsive means, comprising: a housing to .be mounted within said cabin, said housing including wall means defining a reservoir; means carried by said housing forming a restricted orifice to place the reservoir in communication with the interior of the cabin for airflow into and out of said reservoir at a restricted rate to vary the air pressure in the reservoir in accordance with variations in cabin absolute pressure; a pressure responsive capsule mounted within said housing and responsive on the one side to changes in cabin absolute pressure and on the other side to changes in pressure within said reservoir; a pair of contacts, in-

eluding means adapted to be operatively connected to said electro-responsive means of said system; a switch arm carried within said housing and disposed intermediate said contacts, said arm operatively connected to said capsule for movement thereby as said capsule responds to changes in cabin absolute pressure and reservoir pressure whereby said switch arm as it is moved by said capsule into engagement with one or the other of said pair of contacts operatively controls actuation of said electro-responsive means and said discharge valve.

15. A pressure regulating instrument for use in a system for regulating pressure in an aircraft cabin whereinto air is supplied by an air delivery means and from which vitiated air-is discharged through a valve regulated by electro-responsive means, comprising: a housing to be mounted within said cabin, said housing including Wall means defining a reservoir; means carried by said housing forming a restricted orifice to place the reservoir in communication with the interior of the cabin for airflow into and out of said reservoir at a restricted rate to vary the air pressure in the reservoir in accordance with variations in cabin absolute pressure; a pressure responsive capsule mounted Within said housing and responsive on the one side to changes in cabin absolute pressure and on the other side to changes in pressure within said reservoir; switch means mounted within said housing including means adapted to be operatively connected to said electro-responsive means; and switch actuator means operatively connected to said capsule and operable thereby as said capsule responds to changes in cabin absolute pressure and reservoir pressure to actuate said switch means to control operation of the electro-responsive control means of said discharge valve.

16. An instrument for controllably regulating pressure within an aircraft cabin Whereinto air is continuously supplied by an air delivery means and having means for varying the rate of air discharged therefrom, comprising: a housing to be mounted within said cabin, said housing including Wall means defining a reservoir; means carried by said housing forming a restricted orifice to place the reservoir in communication with the interior of said cabin for airflow into and out of said reservoir at a restricted rate to vary the air pressure in the reservoir in accordance with variations in cabin absolute pressure; a pair of contacts; means for mounting said contacts within said housing, said mounting means including means adapted to operatively connect said contacts respectively to pressure increase and pressure decrease control means actuating the air discharge varying means of said system; a pivotally mounted lever having one end thereof disposed between said contacts; a pressure responsive device subjected to the difference between cabin absolute pressure and reservoir pressure; means interconnecting said lever and said device whereby said lever is pivotally moved by said device as the same responds to changes in the difference between said pressures to move the one end of said lever into engagement with one or the other of said contacts to operatively control actuation of said pressure increase and pressure decrease control means; means for conjointly moving said contacts relative to said one end of the lever; and means for moving said contacts relative to each other to vary the relative spacing therebetween.

WOLFGANG B. KLEMPERE-R.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,557,822 Foulk Oct. 20, 1925 1,634,961 Reeves July 5, 192'? 1,935,736 Colvin et a1. Nov. 21, 1933 2,002,057 Gregg May 21, 1935 2,077,267 Rogers .Apr. 13, 1937 2,208,554 Price July 16, 1940 2,307,199 Cooper Jan. 5, 1943 2,396,116 Noxon Mar. 5, 1946 2,549,690 Klemperer Apr. 17, 1951 

